Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
h,w=map(int,input().split())
maze=[['#' for i in range(w+2)]]+[['#']+[x=='#' for x in input()]+['#'] for i in range(h)]+[['#' for i in range(w+2)]]
f=0
for i in range(1,h+1):
  for j in range(1,w+1):
    if maze[i][j]:
	    f+=1
z=0
pos=deque([(1,1,0)])
while pos:
    x,y,c=pos.popleft()
    if (x,y)==(h,w):
        print(h*w-f-c-1)
        z=1
        break
    elif maze[x][y]:
        continue
    pos.append((x-1, y, c+1))
    pos.append((x+1, y, c+1))
    pos.append((x, y-1, c+1))
    pos.append((x, y+1, c+1))
    maze[x][y] = True
if z==0:
	print(-1)